Assange, who has been taunting world leaders by revealing sometimes embarrassing U.S. secrets, is now the center of an international tug of war, with his opponents calling him a dangerous agent against state secrecy and his supporters calling him a champion of the public's right to know.

British authorities were holding Assange without bail after the 39-year-old Australian surrendered at a London police station early Tuesday following weeks of living under the radar. He now faces a legal proceeding next Tuesday to fight extradition to Sweden for questioning in connection with the alleged sexual assaults, which he denies.

But to bring Assange to trial on American soil could be increasingly messy. Not only would the United States need to come up with creative charges that may be difficult to prove, it would also have to launch a laborious extradition request with Sweden, a country known for protecting asylum seekers.

In addition, if British authorities grant the Swedish request, Assange would be flown to a country that shares a significantly stricter extradition treaty with the United States. Swedish authorities said Tuesday that they would seriously weigh any request but noted that their treaty with the United States does not cover crimes that are political or military in nature.

"If and when a U.S. request comes, it must be built with some sort of evidence and would be complicated if the same act is not punishable under Swedish law," said Nils Rekke, head of the legal department at the Swedish prosecutor's office in Stockholm. It would also depend, he said, on whether any crime "is considered political or military, which are omitted" from the extradition treaty.

Assange has argued that the allegations against him are politically motivated.

U.S. officials have been investigating whether Assange, as head of WikiLeaks, can be charged for disseminating sensitive documents, including detailed accounts of the wars in Afghanistan and Iraq and embarrassing personal opinions of world leaders held by U.S. diplomats.

Given the broader extradition treaty Washington enjoys with London, analysts say that going after Assange while he is still on British soil would prove the surer path. Nevertheless, his arrest may not affect the pace of the investigation in the United States, according to U.S. officials and experts on the laws of extradition.

The U.S. attorney's office in Alexandria and the FBI are conducting what Justice Department officials have described as an aggressive criminal probe that sources familiar with the inquiry say could lead to charges under the Espionage Act. But prosecutions under the 1917 act are highly complex, and sources familiar with the investigation have said that no criminal charges are imminent.

U.S. officials, who spoke on the condition of anonymity because they were not authorized to discuss the probe, indicated Tuesday that they were unlikely to quickly put together a criminal case just to seek Assange's extradition. That could mean that Assange is instead extradited to Sweden to face the sex crime charges there.